Fullerene-containing polymer, producing method thereof, and photorefractive composition

ABSTRACT

A photorefractive composition comprising a polymer prepared by living radical polymerization, wherein: the living radical polymerization is carried out using a monomer, a polymerization initiator, transition metal catalyst and a ligand capable of reversibly forming a complex with the transition metal catalyst, and the polymer comprises at least one of a repeat unit including a moiety having charge transport ability and a repeat unit including a moiety having non-linear-optical ability, and the polymer contains fullerene moiety(ies) at the polymer terminal position.

FIELD OF THE INVENTION

The invention relates to a polymer, producing method thereof, andphotorefractive composition. More particularly, the invention relates topolymers and copolymers that contain fullerene moiety at the backbone(co)polymer chain, and to methods of making such polymers. Also, theinvention relates to the compositions that include such polymer andprovide photorefractive capabilities.

BACKGROUND OF THE INVENTION

Photorefractivity is a phenomenon in which the refractive index of amaterial can be altered by changing the electric field within thematerial, such as by intense laser beam irradiation. The change ofrefractive index is achieved by a series of steps, including: (1) chargegeneration by laser irradiation, (2) charge transport, resulting inseparation of positive and negative charges, and (3) trapping of onetype of charge (charge delocalization), (4) formation of a non-uniforminternal electric field (space-charge field) as a result of chargedelocalization, and (5) refractive index change induced by thenon-uniform electric field.

Therefore, good photorefractive properties can be seen only formaterials that combine good charge generation, good charge transport, orphotoconductivity, and good electro-optical activity.

Photorefractive materials have many promising applications, such ashigh-density optical data storage, dynamic holography, optical imageprocessing, phase conjugated mirrors, optical computing, paralleloptical logic, and pattern recognition.

Originally, the photorefractive effect was found in a variety ofinorganic electro-optical (EO) crystals, such as LiNbO₃. In thesematerials, the mechanism of the refractive index modulation by theinternal space-charge field is based on a linear electro-optical effect.

In 1990 and 1991, the first organic photorefractive crystal andpolymeric photorefractive materials were discovered and reported. Suchmaterials are disclosed, for example, in U.S. Pat. No. 5,064,264, toDucharme et al. Organic photorefractive materials offer many advantagesover the original inorganic photorefractive crystals, such as largeoptical nonlinearities, low dielectric constants, low cost, lightweight,structural flexibility, and ease of device fabrication. Other importantcharacteristics that may be desirable depending on the applicationinclude sufficiently long shelf life, optical quality, and thermalstability. These kinds of active organic polymers are emerging as keymaterials for advanced information and telecommunication technology.

In recent years, efforts have been made to optimize the properties oforganic, and particularly polymeric, photorefractive materials. Asmentioned above, good photorefractive properties depend upon good chargegeneration, good charge transport, also known as photoconductivity, andgood electro-optical activity. Various studies that examine theselection and combination of the components that give rise to each ofthese features have been done.

The photoconductive or charge transport capability is frequentlyprovided by incorporating materials containing phenyl amine derivativegroups. Some examples of phenyl amine derivative groups are carbazole,triphenyl amine, or tetraphenyldiamine group containing derivatives.

Typical examples of carbazole, triphenyl amine, or tetraphenyldiaminegroup containing derivatives are carbazoyl alkyl derivative, carbazoyltype polymer, polyvinylcarbazole (PVK), triphenyl amine alkylderivative, triphenyl amine type polymer, and tetraphenyldiamine (TPD)group containing polymers.

The electro-optical capability is generally provided by includingchromophore or dye compounds, such as an azo-type or other electrondonor and acceptor functional group containing derivatives.

The charge generation capability can be generally obtained by a materialknown as a sensitizer, including wide range of fullerene derivatives,which can generate photo-electron by light irradiation.

Usually, fullerene derivative compounds provide better photo-electrongeneration ability than other fluorenone derivatives, which also work asa good photo-electron generation sensitizer.

The fullerenes are general novel class materials which are composed ofonly carbon atom and have ball shape chemical structure. Typically, C₆₀is known as a prototype. As other examples, C₇₀, C₇₆, C₇₈, C₈₄ and theirmixture are also categolized as fullerenes. Furthermore, chemicallymodified derivatives are also belong to a class material of fullerene.The soccer-ball-shaped molecules possess three-dimensional p-delocalizedelectrons, a property that gives rise to a large nonresonant,instantaneous response.

The photorefractive composition may be made simply by mixing thesemolecular components that provide the individual properties requiredinto a host polymer matrix. Several composition which showed goodphotorefractivity have been developed and studied.

For example, in PVK-based materials, the space-charge field that givesrise to the change in refractive index is built up on a sub-second timescale because of the high charge transport ability of the PVK matrix.

Japanese Patent Application Laid-open JP-A 1998-333195, to Showa Denko,discloses acrylate-based polymers incorporating triphenylamine groups ascharge transport agents. Fast response times (50 msec. at 70 V/μm biasedvoltage), although there is no description or data regarding diffractionefficiency.

Also, there are other approach to put the photoconductivity (chargetransport) capability part and the non-linear optical capability intoone single polymer chain. It has been recognized that it would bedesirable to prepare bi-functionalised photorefractive polymers, thatis, polymers in which both the photoconductivity and the non-linearoptical capability reside within the polymer itself

As examples of these type polymers, PVK polymers in which some of thecarbazole groups are tricyanovinylated have been made (N. Peyghambarianet al., Applied Phys. Lett., 1992, 60, 1803). Subsequently, the samegroup has reported PVK-based materials with an fast response time and avery high photoconductivity. (N. Peyghambarian et al., J. Mater. Chem.,1999, 9, 2251).

A number of efforts at materials improvement have usedmethacrylate-based polymers and copolymers that include photoconductiveand chromophore side groups. A paper by T. Kawakami and N. Sonoda,(Applied Phys. Lett., 1993, 62, 2167.) discloses acrylate-based polymerscontaining dicyanovinylideneyl phenylamines as charge transport groups.

A report by H. Sato et al., (Technical report of IEICE., 1995,OME-95-53, OPE95-94, 43) describes the preparation of several copolymershaving both charge transport components and non-linear opticalcomponents in the side groups of the copolymer. However, the chargetransport speeds seem to be too slow for good photorefractive materials.

A paper by Van Steenwickel et al. (Macromolecules, 2000, 33, 4074)describes acrylate-based polymers that include carbazole-based sidechains and several stilbene-type side chains. The paper cites a highdiffraction efficiency of 60% at 58 V/μm, but a slow response time ofthe sub-second order.

A paper by Y. Chen et al. (Modern Optics, 1999, 46, 1003) discusses amethacrylate polymer that has both carbazole-type side chains to providecharge transport capability and nitrophenyl azo-type side chains toprovide non-linear optical capability. The materials again show slowresponse times of over 20 sec.

All of the materials described above utilize low molecular weightsensitizer molecule as an additive. Particularly, fullerene derivativesare mostly used for a sensitizer, because fullerene gives the mostefficient photo-electron generation. However, fullerene derivatives havevery low solubility with either solvents or other components. Sometimesthe fullerenes are clustered out into small solid particle in thephotorefractive composition, due to the small solubility intocomponents. This clustering phenomenon make compositions lesstransparent composition or light scattering, which leads to poorphotorefractivity. Furthermore, the small solid particle can causeelectric breakdown, when high voltage is applied onto the photorefrativecomposition during sample measurement. In order to avoid this kind ofproblem, new type of the fullerene incorporation methods have beendemanded.

In recent years, a new type of polymerization, termed living radicalpolymerization, has been developed for polymerization of functionalmonomers, including methacrylate and styrene derivatives. Living radicalpolymerization differs from conventional radical polymerization in thatthe polymer growth terminals can be temporarily protected by protectionbonding. This enables polymerization to be well controlled, includingbeing stopped and started at will.

This process can be used to prepare homopolymers and copolymers,including block copolymers. Details of the living radical polymerizationmethod are described in the literature. They may be found, for example,in the following papers:

1. T. Patten et al., “Radical polymerization yielding polymers withMw/Mn ˜1.05 by homogeneous atom transfer radical polymerization”,Polymer Preprints, 1996, 37, 575.

2. Matyjasewski et al., “Controlled/living radical polymerization.Halogen atom transfer radical polymerization promoted by a Cu(I)/Cu(II)redox process”, Macromolecules, 1995, 28, 7901.

3. M. Sawamoto et al., “Ruthenium-mediated living radical polymerizationof methyl methacrylate”, Macromolecules, 1996, 29, 1070.

Living radical polymerization is also described in U.S. Pat. No.5,807,937 to Carnegie-Mellon University, which is incorporated herein byreference in its entirety.

The only example known to the present inventor of fullerene-containingpolymer preparation by living radical polymerization is in a paper by F.M. Li et. al. (Macromolecules, 2000, 33, 1948). This reference disclosesthe polymerization for a C₆₀ fullerene-containing styrene polymer, usinga copper halide catalysis. No photorefractive or electro-opticalperformance data are reported in the citation.

SUMMARY OF THE INVENTION

The object of the present invention is to provide polymers andcopolymers that contain fullerene moiety at the backbone (co)polymerchain, and to methods of making such polymers. Also, the inventionrelates to the compositions that include polymer which exhibits highphotorefractivity and is desirably used for the photorefractivecomposition, and producing method thereof.

A first aspect of the present invention is a polymer represented by aformula selected from the group consisting of formulae (I), (II), (III)and (IV):

wherein R₀ represents a hydrogen atom or alkyl group with up to 10carbons; R is selected from the group consisting of a hydrogen atom, alinear alkyl group with up to 10 carbons, a branched alkyl group with upto 10 carbons, and an aromatic group with up to 10 carbons; C ball is afunctional group selected from the class of fullerenes; A represents arepeating structure comprising at least one of the below repeating unit1 and repeating unit 2;

wherein p is an integer of 2 to 6; A′ represents a repeating structurecomprising at least one of the below repeating unit 1 and repeating unit2;

wherein Z is represented by a structure selected from the groupconsisting of structures (i), (ii) and (iii); and Z′ is represented byformula (0);

wherein Q represents an alkylene group, with or without a hetero atom;such as oxygen or sulfur, and preferably Q is an alkylene grouprepresented by (CH₂)p; where p is an integer of about 2 to 6; R₁ isselected from the group consisting of a hydrogen atom, a linear alkylgroup with up to 10 carbons, a branched alkyl group with up to 10carbons, and an aromatic group with up to 10 carbons, and preferably R₁is an alkyl group which is selected from methyl, ethyl, propyl, butyl,pentyl and hexyl; G is a group having a bridge of π-conjugated bond; andEacpt is an electron acceptor group;

wherein the structures (i), (ii) and (iii) are:

wherein Q represents an alkylene group, with or without a hetero atom,such as oxygen or sulfur, and preferably Q is an alkylene grouprepresented by (CH₂)p; where p is an integer of about 2 to 6; andwherein Ra₁, Ra₂, Ra₃, Ra₄, Ra₅, Ra₆, Ra₇, and Ra₈ are independentlyselected from the group consisting of a hydrogen atom, a linear alkylgroup with up to 10 carbons, a branched alkyl group with up to 10carbons, and an aromatic group with up to 10 carbons;

wherein Rb₁-Rb₂₇ are independently selected from the group consisting ofa hydrogen atom, a linear alkyl group with up to 10 carbons, a branchedalkyl group with up to 10 carbons, and an aromatic group with up to 10carbons; and

wherein Rc₁-Rc₁₄ are independently selected from the group consisting ofa hydrogen atom, a linear alkyl group with up to 10 carbons, a branchedalkyl group with up to 10 carbons, and an aromatic group with up to 10carbons.

A second aspect of the present invention is a method for producing afullerene-containing polymer comprising: polymerizing a monomer by aliving radical polymerization technique to form a polymer, wherein themonomer comprises a structure selected from the group consisting of theabove structures (i), (ii) and (iii); and reacting the polymer with afullerene to produce a fullerene-containing polymer, wherein thefullerene-containing polymer is represented by a formula selected fromthe group consisting of the following formulae (Ia), (IIa), (IIIa) and(IVa):

wherein R₀, R, Z, and Cball each have the same meaning as in formula(I); and k is an integer of 10 to 10,000;

wherein R₀, R, Z, and Cball each have the same meaning as in formula(II); and m and n are an integer of 5 to 10,000, respectively;

wherein R₀, Z, and C_(ball) each have the same meaning as in formula(III); and k is an integer of 10 to 10,000;

wherein Z and C_(ball) each have the same meaning as in formula (IV);and k is an integer of 10 to 10,000.

A third aspect of the present invention is a method for producing afullerene-containing polymer comprising: polymerizing a monomer by aliving radical polymerization technique to a polymer, wherein themonomer comprises a structure represented by the above formula (0); andreacting the polymer with a fullerene to produce a fullerene-containingpolymer, wherein the fullerene-containing polymer is represented by aformula selected from the group consisting of the following formulae(Ib), (IIb), (IIIb) and (IVb):

wherein R₀, R, Z′, and C_(ball) each have the same meaning as in formula(I); and k is an integer of 10 to 10,000;

wherein R₀, R, Z′, and Cball each have the same meaning as in formula(II); and m and n are an integer of 5 to 10,000, respectively;

wherein R₀, Z′, and C_(ball) each have the same meaning as in formula(III); and k is an integer of 10 to 10,000;

wherein Z′ and C_(ball) each have the same meaning as in formula (IV);and k is an integer of 10 to 10,000.

A fourth aspect of the present invention is a method for producing afullerene-containing polymer comprising: copolymerizing at least a firstmonomer and a second monomer by a living radical polymerizationtechnique to form a polymer, wherein the first monomer comprises astructure selected from the group consisting of the above structures(i), (ii) and (iii); and reacting the polymer with a fullerene toproduce a fullerene-containing polymer, wherein the fullerene-containingpolymer is represented by a formula selected from the group consistingof the following formulae (Ic), (IIc), (IIIc) and (IVc):

wherein R₀, R, Z, Z′, and C_(ball) each have the same meaning as informula (I); x is an integer of 5 to 10,000; and y is an integer of 5 to10,000;

wherein R₀, R, Z, Z′, and Cball each have the same meaning as in formula(II); x is an integer of 5 to 10,000; y is an integer of 5 to 10,000; ris an integer of 5 to 10,000; and s is an integer of 5 to 10,000;

wherein R₀, Z, Z′, and C_(ball) each have the same meaning as in formula(III); and x is an integer of 5 to 10,000; and y is an integer of 5 to10,000;

wherein Z, Z′, and C_(ball) each have the same meaning as in formula(IV); and x is an integer of 5 to 10,000; and y is an integer of 5 to10,000.

A fifth aspect of the present invention is a composition comprising asensitizer and a polymer according to first aspect of the presentinvention, wherein the composition exhibits photorefractive ability.

A sixth aspect of the present invention is a composition comprising afullerene-containing polymer obtained by reacting a polymer prepared byliving radical polymerization with a fullerene, wherein: (a) the livingradical polymerization is carried out using a monomer, a polymerizationinitiator, transition metal catalyst and a ligand capable of reversiblyforming a complex with the transition metal catalyst, (b) the polymercomprises at least one of a first repeat unit including a moiety havingcharge transport ability and a second repeat unit including a moietyhaving non-linear-optical ability, and (c) the composition exhibitsphotorefractive ability. One or both of the photoconductive (chargetransport) and non-linear optical components are incorporated into thechemical structure of the polymer itself, typically as side groups.

The polymer differs from photorefractive polymers previously known inthe art, because it contains the fullerene group in the polymer chainsand is prepared by living radical polymerization, preferably by using atransition metal catalyst.

With respect to the invention point, it was discovered by the inventorthat living radical polymerization techniques could be adapted toprovide polymers with improved properties for use in photorefractivepolymers. Living radical polymerization technique by the inventor makesavailable to the art a number of innovative features, including use ofacrylate-based monomers incorporating charge transport groups and/ornon-linear-optical (chromophore) groups, use of transition metalcatalyst systems for preparation of photorefractive materials, and useof a monomer incorporating a chromophore precursor group.

DETAILED DESCRIPTION OF THE INVENTION

The photorefractive polymer matrix that is composed of at leastfullerene derivatives, along with a component that providesphotoconductive or charge transport ability and a component thatprovides non-linear optical ability. Optionally, the polymer may alsoinclude other components as desired, such as plasticizer components.

One or both of the photoconductive and non-linear optical components areincorporated as functional groups into the polymer structure, typicallyas side groups.

The group that provides the charge transport or photoconductivefunctionality may be any group known in the art to provide suchcapability. If this group is to be attached to the polymer matrix as aside chain, then the group should be capable of incorporation into amonomer that can be polymerized to form the polymer matrix of thecomposition.

Preferred photoconductive groups are phenyl amine derivatives,particularly carbazoles and di-/tri-/tetra-phenyl diamine.

Most preferably the moiety that provides the photoconductivefunctionality is chosen from the group of phenyl amine derivativesconsisting of the following side chain structures (i) to (iii):

wherein Q represents an alkylene group, with or without a hetero atom,such as oxygen or sulfur, and preferably Q is an alkylene grouprepresented by (CH₂)p; where p is an integer of about 2 to 6; andwherein Ra₁, Ra₂, Ra₃, Ra₄, Ra₅, Ra₆, Ra₇, and Ra₈ are independentlyselected from the group consisting of a hydrogen atom, a linear alkylgroup with up to 10 carbons, a branched alkyl group with up to 10carbons, and an aromatic group with up to 10 carbons;

wherein Q represents an alkylene group, with or without a hetero atom,such as oxygen or sulfur, and preferably Q is an alkylene grouprepresented by (CH₂)p; where p is an integer of about 2 to 6; andwherein Rb₁-Rb₂₇ are independently selected from the group consisting ofa hydrogen atom, a linear alkyl group with up to 10 carbons, a branchedalkyl group with up to 10 carbons, and an aromatic group with up to 10carbons; and

wherein Q represents an alkylene group, with or without a hetero atom,such as oxygen or sulfur, and preferably Q is an alkylene grouprepresented by (CH₂)p; where p is an integer of about 2 to 6, andwherein Rc₁-Rc₁₄ are independently selected from the group consisting ofa hydrogen atom, a linear alkyl group with up to 10 carbons, a branchedalkyl group with up to 10 carbons, and an aromatic group with up to 10carbons.

Likewise, the chromophore or group that provides the non-linear opticalfunctionality may be any group known in the art to provide suchcapability. If this group is to be attached to the polymer matrix as aside chain, then the group, or a precursor of the group, should becapable of incorporation into a monomer that can be polymerized to formthe polymer matrix of the composition.

The chromophore or group that provides the non-linear opticalfunctionality used in the present invention is represented by formula(0):

wherein Q represents an alkylene group, with or without a hetero atom;such as oxygen or sulfur, and preferably Q is an alkylene grouprepresented by (CH₂)p; where p is an integer of about 2 to 6; R₁ isselected from the group consisting of a hydrogen atom, a linear alkylgroup with up to 10 carbons, a branched alkyl group with up to 10carbons, and an aromatic group with up to 10 carbons, and preferably R₁is an alkyl group which is selected from methyl, ethyl, propyl, butyl,pentyl and hexyl; G is a group having a bridge of π-conjugated bond; andEacpt is an electron acceptor group.

In the above definition, by the term “a bridge of π-conjugated bond”, itis meant a molecular fragment that connects 2 to 10 chemical groups byπ-conjugated bond. A π-conjugated bond contains covalent bonds betweenatoms that have σ bonds and π bonds formed between two atoms by overlapof their atomic orbitals (s+p hybrid atomic orbitals for σ bonds; patomic orbitals for π bonds).

By the term “electron acceptor”, it is meant a group of atoms with ahigh electron affinity that can be bonded to a π-conjugated bridge.Exemplary acceptors, in order of increasing strength, are:

C(O)NR²<C(O)NHR<C(O)NH₂<C(O)OR<C(O)OH<C(O)R<C(O)H<CN<S(O)₂R<NO₂

As typical exemplary electron acceptor groups, functional groups whichis described in prior of art U.S. Pat. No. 6,267,913 and shown in thefollowing structure figure can be used.

wherein R is selected from the group consisting of a hydrogen atom, alinear alkyl group with up to 10 atoms, a branched alkyl group with upto 10 atoms, and an aromatic group with up to 10 carbons.

Preferred chromophore groups are aniline-type groups or dehydronaphtylamine groups.

Most preferably the moiety that provides the non-linear opticalfunctionality is such a case that G in formula (0) is represented by astructure selected from the group consisting of the structures (iv), (v)and (vi);

wherein, in both structures (iv) and (v), Rd₁-Rd₄ are each independentlyselected from the group consisting of a hydrogen atom, a linear alkylgroup with up to 10 atoms, a branched alkyl group with up to 10 atoms,and an aromatic group with up to 10 carbons, and preferably Rd₁-Rd₄ areall hydrogen; R₂ is selected from the group consisting of a hydrogenatom, a linear alkyl group with up to 10 atoms, a branched alkyl groupwith up to 10 atoms, and an aromatic group with up to 10 carbons;

wherein R₇, R₇′, R₇″, and R₇′″ each independently represent hydrogen ora linear or branched alkyl group with up to 10 carbons; and

wherein Eacpt in formula (0) is an electron acceptor group andrepresented by a structure selected from the group consisting of thestructures;

wherein R₉, R₁₀, R₁₁ and R₁₂ are each independently selected from thegroup consisting of a hydrogen atom, a linear alkyl group with up to 10atoms, a branched alkyl group with up to 10 atoms, and an aromatic groupwith up to 10 carbons.

A preferred polymer used for the photorefractive composition is thefollowing formulae (Ia), (IIa), (IIIa), (IVa), (Ib), (IIb), (IIIb),(IVb), (Ic), (IIc), (IIIc) and (IVc):

wherein R₀, R, Z and C ball each have the same meaning as in formula(I); and k is an integer of 10 to 10,000;

wherein R₀, R, Z and C ball each have the same meaning as in formula(I); and m and n are an integer of 5 to 10,000, respectively;

wherein R₀, Z and C ball each have the same meaning as in formula (I);and k is an integer of 10 to 10,000;

wherein Z and C ball each have the same meaning as in formula (I); and kis an integer of 10 to 10,000;

wherein R₀, R, Z′ and C ball each have the same meaning as in formula(I); and k is an integer of 10 to 10,000;

wherein R₀, R, Z′ and C ball each have the same meaning as in formula(I); and m and n are an integer of 5 to 10,000, respectively;

wherein R₀, Z′ and Cball each have the same meaning as in formula (I);and k is an integer of 10 to 10,000;

wherein Z′ and Cball each have the same meaning as in formula (I); and kis an integer of 10 to 10,000;

wherein R₀, R, Z, Z′ and Cball each have the same meaning as in formula(I); x is an integer of 5 to 10,000; and y is an integer of 5 to 10,000;

wherein R₀, R, Z, Z′ and Cball each have are the same meaning as informula (I); x is an integer of 5 to 10,000; y is an integer of 5 to10,000; r is an integer of 5 to 10,000; and s is an integer of 5 to10,000;

wherein R₀, Z, Z′ and Cball each have the same meaning as in formula(I); and x is an integer of 5 to 10,000; and y is an integer of 5 to10,000;

wherein Z, Z′ and Cball each have the same meaning as in formula (I);and x is an integer of 5 to 10,000; and y is an integer of 5 to 10,000.

The polymer matrix is preferably synthesized from a monomerincorporating at least one of the above photoconductive groups or one ofthe above chromophore groups. The inventor has recognized that a numberof physical and chemical properties are desirable in the polymer matrix.It is preferred if the polymer itself incorporates both a chargetransport group and a chromophore group, so the ability of the monomerunits to form copolymers is preferred. Physical properties of the formedpolymer that are of importance are the molecular weight and the glasstransition temperature, Tg. Also, it is valuable and desirable, althoughnot essential, that the polymer should be capable of being formed intofilms, coatings and shaped bodies of various kinds by standard polymerprocessing techniques, such as solvent coating, injection molding andextrusion.

In the present invention, the polymer generally has a weight averagemolecular weight, Mw, of from about 3,000 to 500,000, preferably fromabout 5,000 to 100,000. The term “weight average molecular weight” asused herein means the value determined by the GPC (gel permeationchromatography) method in polystyrene standards, as is well known in theart.

For good photorefractive properties, the photorefractive compositionshould be substantially amorphous and non-crystalline or non-glassyunder the conditions of use. Therefore, it is preferred that thefinished photorefractive composition has a relatively low glasstransition temperature, Tg, such as below about 50° C., more preferablybelow about 40° C. Preferred temperature ranges for the Tg are 10-50°C., most preferably 20-40° C. If the pure polymer itself has a glasstransition temperature higher than these preferred values, which willgenerally be the case, components may be added to lower the Tg, asdiscussed in more detail below.

Nevertheless, it is preferred that the polymer itself has a relativelylow glass transition temperature, by which the inventors mean a Tg nohigher than about 125° C., more preferably no higher than about 120° C.,and most preferably no higher than about 110° C. or 100° C.

A relatively low glass transition temperature is preferred because thegreater mobility of polymer chains that polymers exhibit close to orabove their glass transition temperature gives higher orientation duringvoltage application, and leads to better performance, such as highphotoconductivity, fast response time and high diffraction efficiency,of the photorefractive device.

In principle, as the polymer backbone matrices of the invention,including, any polymer chain can be used as long as the correspondingmonomers can be polymerized by living radical polymerization method.

Preferred types of backbone units are those based on (meth)acrylates orstyrene. Particularly preferred are methacrylate-based monomers, andmost preferred are acrylate monomers. The first polymeric materials toinclude photoconductive functionality in the polymer itself were thepolyvinyl carbazole materials developed at the University of Arizona.However, these polyvinyl carbazole polymers tend to become viscous andsticky when subjected to the heat-processing methods typically used toform the polymer into films or other shapes for use in photorefractivedevices.

In contrast, preferred materials of the present invention, andparticularly the (meth)acrylate-based, and more specificallymethacrylate-based, polymers, have much better thermal and mechanicalproperties. That is, they provide better workability during processingby injection-molding or extrusion, for example. This is particularlytrue when the polymers are prepared by living radical polymerization, asdescribed below, since this method yields a polymer product of lowerviscosity than would be the case for the same polymer prepared by othermethods.

Particular examples of monomers including a phenyl amine derivativegroup as the charge transport component are carbazolylpropyl(meth)acrylate monomer; 4-(N,N-diphenylamino)-phenylpropyl(meth)acrylate; N-[(meth)acroyloxypropylphenyl]-N,N′,N′-triphenyl-(1,1′-biphenyl)-4,4′-diamine;N-[(meth)acroyloxypropylphenyl]-N′-phenyl-N,N′-di(3-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine;andN-[(meth)acroyloxypropylphenyl]-N′-phenyl-N,N′-di(4-buthoxyphenyl)-(1,1′-biphenyl)-4,4′-diamine.Such monomers can be used singly or in mixtures of two or more monomers.

Particular examples of monomers including a chromophore group as thenon-linear optical component are N-ethyl, N-4-dicyanomethylidenylacrylate and N-ethyl,N-4-dicyanomethylidenyl-3,4,5,6,10-pentahydronaphtylpentyl acrylate.

In light of the desired features, the inventor has recognized that therecently developed polymerization technique known as living radicalpolymerization has the potential for preparing polymers with unusuallygood photorefractive properties. In particular, living radicalpolymerization has the potential to form polymers with unusually lowpolydispersity, such as less than 2.5, preferably less than 2.0. Livingradical polymerization can also be used to form random copolymers andblock copolymers, as discussed in more detail below.

Diverse polymerization techniques are known in the art. One suchtechnique is radical polymerization, which is typically carried out byusing an azo-type initiator, such as AIBN (azoisobutyl nitrile).

In conventional radical polymerization, the polymer growth terminal isin the active radical state, so it is easy for unwanted side reactionsto occur, such as bimolecular coupling or disproportionation, generallymaking it difficult to achieve precise control of polymerization. As aresult, this technique is not attractive for preparing photorefractivepolymer materials.

On the other hand, as stated above, living radical polymerization is anew technique that offers the opportunity to prepare polymers withproperties tailored to achieve improved photorefractive capability.Living radical polymerization differs from conventional radicalpolymerization in that the polymer growth terminals are temporarilyprotected by protection bonding. Through reversibly and radicallysevering this bond, it is possible to control and facilitate the growthof polymer molecules. For example, in a polymerization reaction, aninitial supply of monomer can be completely consumed and growth can betemporarily suspended. However, by adding another monomer of the same ordifferent structure, it is possible to restart polymerization.Therefore, the position of functional groups within the polymer can becontrolled.

Although various polymerization techniques are known to the art and maybe used in the invention, it is preferred, therefore, to prepare thepolymer matrix materials of the invention by living radicalpolymerization, and the inventor has developed customized procedures forso doing.

Details of the living radical polymerization method are described in theliterature. They may be found, for example, in the following papers:

T. Patten et al., “Radical polymerization yielding polymers withMw/Mn˜1.05 by homogeneous atom transfer radical polymerization”, PolymerPreprints, 1996, 37, 575.

K. Matyjasewski et al., “Controlled/living radical polymerization.Halogen atom transfer radical polymerization promoted by a Cu(I)/Cu(II)redox process”, Macromolecules, 1995, 28, 7901.

M. Sawamoto et al., “Ruthenium-mediated living radical polymerization ofmethyl methacrylate”, Macromolecules, 1996, 29, 1070.

Living radical polymerization is also described at length in U.S. Pat.No. 5,807,937 to Carnegie-Mellon University, which is incorporatedherein by reference in its entirety.

Briefly, living radical polymerization technique of the inventioninvolves the use of a polymerization initiator, transition metalcatalyst and a ligand (an activating agent) capable of reversiblyforming a complex with the transition metal catalyst.

The polymerization initiator is typically a halogen-containing organiccompounds. After polymerization, this initiator or components of theinitiator are attached to the polymer at both polymer terminals. Thepolymerization initiator preferably used is an ester-based orstyrene-based derivative containing a halogen in the α-position.

The polymerization initiator is preferably shown by the followingformula (I″), (II″) or (III″).

wherein R₀ represents a hydrogen atom or alkyl group with up to 10carbons; and R is selected from the group consisting of a hydrogen atom,a linear alkyl group with up to 10 carbons, a branched alkyl group withup to 10 carbons, and an aromatic group with up to 10 carbons;

wherein R₀ represents a hydrogen atom or alkyl group with up to 10carbons.

Particularly preferred are 2-bromo(or chloro) methylpropionic acid, orbromo(or chloro)-1-phenyl derivatives. Specific examples of thesederivatives include ethyl 2-bromo(or chloro)-2-methylpropionate, ethyl2-bromo(or chloro)propionate, 2-hydroxyethyl 2-bromo(orchloro)-2-methylpropionate, 2-hydroxyethyl 2-bromo(or chloro)propionate,and 1-phenyl ethyl bromide(chloride).

Instead of a mono bromo(chloro) type initiator, a di-bromo(chloro) typeinitiator, such as dibromo(chloro) ester derivative, can be used. Suchinitiators are represented by the formula (IV″):

wherein R₀ represents independently a hydrogen atom or alkyl group withup to 10 carbons; and p is 2 to 6.

Of these initiators, most preferred is ethylene bis(2-bromo(chloro)-2-methylpropionate). By using this initiator, the inventor hasdiscovered that block copolymers, and particularly A-B-A type or B-A-Btype block copolymers, can be produced very efficiently.

In the process of the invention, the polymerization initiator isgenerally used in an amount of from 0.01 to 20 mol %, preferably from0.1 to 10 mol %, and more preferably from 0.2 to 5 mol %, per mole ofthe sum of the polymerizable monomers.

Various types of catalysts are known, including perfluoroalkyl iodidetype, TEMPO (phenylethoxy-tetramethylpiperidine) type, and transitionmetal type. The inventor has discovered that high-quality polymers canbe made by using transition-metal catalysts, which are safer, simpler,and more amenable to industrial-scale operation than TEMPO-typecatalysts. Therefore, in the process of the invention a transition-metalcatalyst is preferred.

Non-limiting examples of transition metals that may be used include Cu,Ru, Fe, Rh, V, and Ni. Particularly preferred is Cu. Typically, but notnecessarily, the transition metal is used in the form of the metalhalide (chloride, bromide, etc.).

The transition metal in the form of a halide or the like is generallyused in the amount of from 0.01 to 3 moles, and preferably from 0.1 to 1mole, per mole of polymerization initiator.

The activating agent (ligand) is an organic ligand of the type known inthe art that can be reversibly coordinated with the transition metal asa center to form a complex. The ligand preferably used is a bipyridinederivative, mercaptans derivative, trifluorate derivative, or the like.When complexed with the activating ligand, the transition metal catalystis rendered soluble in the polymerization solvent. In other words, theactivating agent serves as a co-catalyst to activate the catalyst, andstart the polymerization.

The ligand is used in an amount of normally from 1 to 5 moles, andpreferably from 2 to 3 moles, per mole of transition metal halide.

The use of the polymerization initiator and the activating agent in theabove recommended proportions makes it possible to provide good resultsin terms of the reactivity of the living radical polymerization and themolecular weight and weight distribution of the resulting polymer.

In the present invention, living radical polymerization can be carriedout without a solvent or in the presence of a solvent, such as butylacetate, toluene or xylene.

To initiate the polymerization process, the monomer(s), polymerizationinitiator, transition metal catalyst, activating agent and solvent areintroduced into the reaction vessel. As the process starts, the catalystand initiator form a radical, which attacks the monomer and starts thepolymerization growth.

The living radical polymerization is preferably carried out at atemperature of from about 70° C. to 130° C., and is allowed to continuefor about 1 to 100 hours, depending on the desired final molecularweight and polymerization temperature, and taking into account thepolymerization rate and deactivation of catalyst.

By carrying out the living radical polymerization technique based on theteachings and preferences given above, it is possible to preparehomopolymers carrying charge transport or non-linear optical groups, aswell as random or block copolymers carrying both charge transport andnon-linear optical groups. It is possible to prepare such materials withexceptionally good properties, such as response time and diffractionefficiency.

If the polymer is made from monomers that provide only charge transportability, the photorefractive composition of the invention can be made bydispersing a component that possesses non-linear optical propertiesthrough the polymer matrix, as is described in U.S. Pat. No. 5,064,264to IBM, which is incorporated herein by reference. Suitable materialsare known in the art and are well described in the literature, such asin D. S. Chemla & J. Zyss, “Nonlinear Optical Properties of OrganicMolecules and Crystals” (Academic Press, 1987). Also, as described inU.S. Pat. No. 6,090,332 to Seth R. Marder et. al., fused ring bridge,ring locked chromophores that form thermally stable photorefractivecompositions can be used. For typical, non-limiting examples ofchromophore additives, the following chemical structure compounds can beused:

The chosen compound(s) is usually mixed in the matrix charge transporthomopolymer in a concentration of about 1-80 wt %, more preferably 5-50wt %.

On the other hand, if the polymer is made from monomers that provideonly non-linear optical ability, the photorefractive composition of theinvention can be made by mixing a component that possesses chargetransport properties into the polymer matrix, again as is described inU.S. Pat. No. 5,064,264 to IBM. Preferred charge transport compounds aregood hole transfer compounds, for example N-alkyl carbazole ortriphenylamine derivatives.

As an alternative, or in addition, to adding the charge transportcomponent in the form of a dispersion of entities comprising individualmolecules with charge transport capability, a polymer blend can be madeof individual polymers with charge transport and non-linear opticalabilities. For the charge transport polymer, the polymers alreadydescribed above, such as containing phenyl-amine derivative side chains,can be used. Since polymers containing only charge transport groups arecomparatively easy to prepare by conventional techniques, the chargetransport polymer may be made by living radical polymerization or by anyother convenient method.

To prepare the non-linear optical polymer itself, monomers that haveside-chain groups possessing non-linear-optical ability should be used.Non-limiting examples of monomers that may be used are those containingthe following chemical structures:

wherein Q represents an alkylene group with or without a hetero atom,such as oxygen or sulfur, and preferably Q is an alkylene grouprepresented by (CH₂)p; where p is of about 2 to 6; R₀ is a hydrogen atomor methyl group, and R is a linear or branched alkyl group with up to 10carbons; and preferably R is an alkyl group which is selected frommethyl, ethyl, and propyl.

The inventor has discovered a new technique for preparing such polymers.The technique involves the use of a precursor monomer containing aprecursor functional group for non-linear optical ability. Typically,this precursor is represented by the general formula:

wherein R₀ is a hydrogen atom or methyl group, and V is selected fromthe group consisting of the following structures 1 to 3:

wherein, in both structures 1 and 2, Q represents an alkylene group,with or without a hetero atom, such as oxygen or sulfur, and preferablyQ is an alkylene group represented by (CH₂)p; where p is of about 2 to6; and wherein Rd₁-Rd₄ are independently selected from the groupconsisting of a hydrogen atom, a linear alkyl group with up to 10carbons, a branched alkyl group with up to 10 atoms, and an aromaticgroup with up to 10 carbons, and preferably Rd₁-Rd₄ are hydrogen; andwherein R₁ represents a linear or branched alkyl group with up to 10carbons, and preferably R₁ is an alkyl group selected from methyl,ethyl, propyl, butyl, pentyl and hexyls; and

wherein Q represents an alkylene group, with or without a hetero atom,such as oxygen or sulfur, and preferably Q is an alkylene grouprepresented by (CH₂)p; where p is of about 2 to 6; and wherein R₁represents a linear or branched alkyl group with up to 10 carbons, andpreferably R₁ is an alkyl group selected from methyl, ethyl, propyl,butyl, pentyl and hexyls; and wherein R₇, R₇′, R₇″, and R₇′″ eachindependently represent hydrogen or a linear or branched alkyl groupwith up to 10 carbons.

After the precursor polymer has been formed, it can be converted intothe corresponding polymer having non-linear optical groups andcapabilities by a condensation reaction. Typically, the condensationreagent may be selected from the group consisting of

wherein R₉, R₁₀, R₁₁, and R₁₂ are independently selected from the groupconsisting of a hydrogen atom, a linear alkyl group with up to 10carbons, a branched alkyl group with up to 10 carbons, and an aromaticgroup with up to 10 carbons.

The condensation reaction can be done at room temperature for 1-100 hrs,in the presence of a pyridine derivative catalyst. A solvent, such asbutyl acetate, chloroform, dichloromethylene, toluene or xylene can beused. Optionally, the reaction may be carried out without the catalystat a solvent reflux temperature of 30° C. or above for about 1 to 100hours.

The inventor has discovered that use of a monomer containing a precursorgroup for non-linear-optical ability, and conversion of that group afterpolymerization tends to result in a polymer product of lowerpolydispersity than the case if a monomer containing thenon-linear-optical group is used. This is, therefore, preferredtechnique by the invention.

To prepare copolymers, both the non-linear-optical monomer and thecharge transport monomer, each of which can be selected from the typesmentioned above, should be used.

There are no restrictions on the ratio of monomer units. However, as atypical representative example, the ratio of [a (meth)acrylic monomerhaving charge transport ability]/[a (meth)acrylate monomer havingnon-linear optical ability] is between about 4/1 and 1/4 by weight. Morepreferably, the ratio is between about 2/1 and 1/2 by weight. If thisratio is less than about 1/4, the charge transport ability is weak, andthe response time tends to be too slow to give good photorefractivity.On the other hand, if this ratio is more than about 4/1, thenon-linear-optical ability is weak, and the diffraction efficiency tendsto be too low to give good photorefractivity.

In the living radical polymerization method of the invention, themonomer addition sequence is important for achieving the desiredcopolymer structure. For example, to make random copolymers, both thechromophore-containing and the charge-transport-group-containingmonomers can be added at the same time.

However, by adding the monomers sequentially, block type copolymers canbe prepared. For example, to prepare an A-B type block copolymer,wherein polymer block A has charge transport ability and polymer block Bhas non-linear-optical ability, firstly the monomer having chargetransport ability is polymerized, preferably by using a monobromo(chloro) type initiator. Subsequently, the second monomer havingnon-linear-optical ability is added to continue the polymerization. Inthis way, an A-B type block copolymer can be produced. During thispolymerization procedure, the second monomer is added at the time whenthe first monomer is polymerized more than 50% by weight, normally 70%by weight or more, preferably 80% by weight or more, and more preferably90% by weight or more.

On the other hand, if the monomer having non-linear-optical ability ispolymerized first, a B-A type block copolymer can be produced. Similarlyto the above polymerization procedure, the second monomer is added atthe time when the first monomer is polymerized more than 50% by weight,normally 70% by weight or more, preferably 80% by weight or more, andmore preferably 90% by weight or more.

Further, if living radical polymerization is carried out in a mannersuch that, first, the monomer having charge transport ability ispolymerized, then the second monomer having non-linear-optical abilityis added to continue polymerization, and thirdly an additional amount ofthe monomer having charge transport ability is added to continuepolymerization, an A-B-A type block copolymer can be produced. Duringthe successive polymerization procedure, the monomer to be subsequentlyadded is added at the time when the conversion of the monomer which hasbeen previously added exceeds at least 50% by weight, normally 60% byweight or more, preferably 80% by weight or more, and more preferably90% by weight or more.

Moreover, if the above three-stage polymerization is followed by theaddition of the another monomer to continue the polymerization ofmonomers, an A-B-A-B type block copolymer can be produced. From theabove explanation, it will be apparent to those of skill in the art thatthe new methods that the inventor has developed can be used, by changingthe sequence of monomer addition, to produce block copolymers of anydesired type, including, but not limited to B-A-B, B-A-B-A, B-A-B-A-B-A,or A-B-A-B-A type block copolymers.

If the copolymer constitutes two or more of polymer blocks A, the A-typeconstituting blocks need not necessarily be prepared from the samemonomer. Likewise, if the copolymer constitutes two or more of polymerblocks B, the B-type blocks need not necessarily be prepared from thesame monomer. Thus, the individual blocks may be of different formsrepresented by A1, A2, A3, etc. and B1, B2, B3 etc. In this way, a largediversity of polymers, such as A1-B-A2, B1-B2-A, or A1-B 1-A2-B2 can beproduced.

Optionally, other components may be added to the polymer matrix toprovide or improve the desired physical properties mentioned earlier inthis section. As mentioned above, it is preferred that the polymermatrix has a relatively low glass-transition temperature, and beworkable by conventional processing techniques. Optionally, aplasticizer may be added to the composition to reduce the glasstransition temperature and/or facilitate workability. The type ofplasticizer suitable for use in the invention is not restricted; manysuch materials will be familiar to those of skill in the art.Representative typical examples include N-alkylcarbazole anddioctylphthalate. Oligomer-type compounds of the charge transport ornon-linear-optical monomers may also be used to control the Tg of thecomposition.

In general, the smallest amount of plasticizer required to provide asuitable overall Tg for the composition should be used. Compositionswith large amounts of plasticizer tend to have lower stability, as thepolymer matrix and the plasticizer may phase separate over time. Also,the photorefractive properties of the material are diminished bydilution of the active components by the plasticizer.

As discussed above, the invention provides polymers of comparatively lowTg when compared with similar polymers prepared in accordance with priorart methods. The inventor has recognized that this provides a benefit interms of lower dependence on plasticizers. By selecting polymers ofintrinsically moderate Tg and by using methods that tend to depress theaverage Tg, it is possible to limit the amount of plasticizer requiredfor the composition to preferably no more than about 30% or 25%, andmore preferably lower, such as no more than about 20%.

Yet another method to adjust the Tg or improve film formation ability,for example, is to add another monomer, such as an acrylic ormethacrylic acid alkyl ester, as a modifying co-monomer. Examples ofmodifying co-monomers are CH₂═CR₀—COOR wherein R₀ represents a hydrogenatom or methyl group, and R represents a C₂₋₁₄ alkyl group, such asbutylacrylate, ethyl acrylate, propyl acrylate, 2-ethylhexyl(meth)acrylate and hexyl (meth)acrylate.

Like mentioned above, the inventor has already found the effectivenessand advantage for using the living radical polymerization.

On the other hand, as one of most important factors, by using the livingradical polymerization technique, novel type of (co)polymer, whichcontain fullerene group at polymer terminal position can be prepared.

The only example known to the inventor of fullerene-containing polymerpreparation by living radical polymerization is in a paper by F. M. Liet. al. (Macromolecules, 2000, 33, 1948). This reference discloses thepolymerization of a C₆₀ fullerene-containing styrene monomer, using acopper halide catalysis. This citation gave us only example of styrenepolymers. No photorefractive or electro-optical performance data arereported in the citation.

In the F. M. Li et. al., after getting polystyrene by the living radicalpolymerization technique, the fullerene addition at last stage gave thecorresponding fullerene-containing (co)polymers. Before the addition offullerene, polymer purification is not required and fullerene atom(s)can be attached at the polymer terminal position with living radicalcatalysis.

Under this circumstance, the inventor found a useful and easy syntheticmethod for the fullerene-containing polymer by using living radicalpolymerization method. Furthermore, the fullerene-containing polymershowed very good photorefractivity, since the fullerene is well-knowngood photosensitizer. The photorefractive materials of the inventionprovide combinations of desirable properties not previously available tothe art.

Fullerene used in the present invention is selected from the class offullerences, which includes derivatives of the fullerenes. For example,C₆₀, C₇₀, C₇₆, C₇₈, and C₈₄ are exemplified as fullerenes. Furthermore,chemically modified derivatives are also belong to a class material offullerene. The soccer-ball-shaped molecules possess three-dimensionalp-delocalized electrons, a property that gives rise to a largenonresonant, instantaneous response.

Fullerene atom(s) can be attached at the polymer terminal position by anaddition reaction. In the addition reaction, transition metal catalysts,activating agents (ligand), and solvents as described above can be used.

A particularly advantageous feature is the good phase stability of thecomposition. Unlike prior arts inventions, the fullerene, which works asphotosensitizer, is incorporating into the polymer chain. Therefore, thefullerene part is not clustered out or phase separated from the matrixpolymer. Usually, low molecular weight additive fullerene has lowsolubility into other materials and easy tendencies to be clustered out.This behavior resulted in low transmittance of laser light or easybreakdown tendency while applying high voltage on performancemeasurement. However, the polymers of the invention contain thefullerene part in their polymer chains and no chance to be clusteredout. Therefore, the polymers of the invention possess superiortransmittance and durability. These are most important feature.

Another advantageous feature is the fast response time. Response time isthe time for building up of the diffraction grating in thephotorefractive material when exposed to a laser writing beam. Theresponse time of a sample of material may be measured by transientfour-wave mixing (TFWM) experiments, as detailed in the Examples sectionbelow. The data may then be fitted with the following bi-exponentialfunction:

η(t)=A sin² [B(1−a ₁ e ^(−t/J1) −a ₂ e ^(−t/J2))]with

a ₁ +a ₂=1

where η(t) is the diffraction efficiency at time t, and A, B, a₁, and a₂are fitting parameters, J₁ and J₂ are the grating build-up times.Between J₁ and J₂, the smaller number is defined as the response time.

Response time is important because the faster response time means fastergrating build-up, which enables the photorefractive composition to beused for wider applications, such as real-time hologram applications.

Typical response times for known photorefractive materials range fromseconds to sub-seconds. Times longer than 100 ms are common. To theinventor's knowledge, the fastest response time reported so far is 4msec., which was reported by N. Peyghambarian et al. (J. Mater. Chem.,1999, 9, 2251). However, in order to get this fast speed, a high biasedvoltage (95V/μm) is required. Such a high biased voltage may bedifficult in an industrial, rather than a laboratory, environment. Also,this response time was achieved in a composition that used a polyvinylcarbazole polymer, and such polymers become sticky and difficult tohandle during heat processing. In contrast, the methacrylate-based, ormore specifically acrylate-based polymers, that are preferred hereinprovide excellent workability during heat processing and other polymerhandling methods.

In comparison with typical prior art materials, the photorefractivecompositions of the invention provide good response times, such as nomore than about 50 ms, and preferably faster, such as no more than about40 ms, no more than about 35 ms, or no more than about 30 ms.

Yet another advantageous feature is the diffraction efficiency.Diffraction efficiency is defined as the ratio of the intensity of thediffracted beam to the intensity of the incident probe beam, and isdetermined by measuring the intensities of the respective beams.Obviously, the closer to 100% is the ratio, the more efficient is thedevice.

In general, for a given photorefractive composition, a higherdiffraction efficiency can be achieved by increasing the applied biasvoltage.

In comparison with typical prior art materials, the photorefractivecompositions of the invention provide good diffraction efficiencies.

Also, with regard to phase stability, in comparison with typical priorart materials, the photorefractive compositions of the invention providegood phase stability. This invention material can be observed no phaseseparation or some component crystallization, even high temperaturestorage. These phase separation or some component crystallization aredisadvantage, because composition give low transmittance of laser beamswhich means low photorefractivities.

In this case, high temperature storage means the temperature is at 60°C.

Usually the higher storage temperature for photorefractive compositioncan enhance speed of composition deterioration, phase separation, orcomposition crystallization. From standpoint of general applicationview, the stability of samples is important and said to require havingat least 3 months at 60° C. which is said to correspond to 3 years at20° C.

The invention is now further described by the following examples, whichare intended to be illustrative of the invention, but are not intendedto limit the scope or underlying principles in any way.

EXAMPLES Production Example 1

(a) Monomers Containing Charge Transport Groups

A triphenyl diamine type(N-[acroyloxypropylphenyl]-N,N′,N′-triphenyl-(1,1′-biphenyl)-4,4′-diamine)(TPD acrylate, the following structure) was purchased from FujiChemical, Japan:

TPD acrylate monomer was prepared by the following procedure.

In the above procedure, usage of 3-methyl diphenylamine instead ofdiphenylamine and 3-methylphenyl halide instead of phenyl halide canresult in the formation ofN(acroyloxypropylphenyl)-N′-phenyl-N,N′-di(3-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine.

b) Synthesis of a Plascticizer TPD-Ac

The plascticizer TPD-Ac was synthesized from the same intermediate whichwas used for TPD acrylate synthesis according to the following one-stepsynthesis scheme:

TPD alcohol (2.8 g, 5.0 mmol), which was one intermediate for TPDacrylate monomer, was dissolved with dichloromethane (10 mL). Into thissolution, acetic anhydride (0.8 mL, 10.6 mmol) and4-(Dimethylamino)pyridine (100 mg, 0.82 mmol) were added and stirred at50° C. for 16 hr. Water (5 mL) was added to the reaction mixture. Theproducts were extracted with dichloromethane (10 mL). After removal ofdichloromethane, the crude products were purified by silica gel columnchromatography using hexanes-ethyl acetate (1:1) as eluent. The productwas collected. Yield (2.97 g, 93%)

(c) Monomers Containing Non-Linear-Optical Groups

The non-linear-optical precursor monomer5-[N-ethyl-N-4-formylphenyl]amino-pentyl acrylate was synthesizedaccording to the following synthesis scheme:

Step I

Into bromopentyl acetate (5 mL, 30 mmol) and toluene (25 mL),triethylamine (4.2 mL, 30 mmol) and N-ethylaniline (4 mL, 30 mmol) wereadded at room temperature. This solution was heated at 120° C.overnight. After cooling down, the reaction mixture wasrotary-evaporated. The residue was purified by silica gel chromatography(developing solvent: hexane/acetone=9/1). An oily amine compound wasobtained. (Yield: 6.0 g (80%))

Step II

Anhydrous DMF (6 mL, 77.5 mmol) was cooled in an ice-bath. Then, POCl₃(2.3 mL, 24.5 mmol) was added dropwise into the 25 mL flask, and themixture was allowed to come to room temperature. The amine compound (5.8g, 23.3 mmol) was added through a rubber septum by syringe withdichloroethane. After stirring for 30 min., this reaction mixture washeated to 90° C. and the reaction was allowed to proceed for overnightunder an argon atmosphere.

On the next day, the reaction mixture was cooled, and poured into andextracted by ether. The ether layer was washed with potassium carbonatesolution and dried over anhydrous magnesium sulfate. After removing themagnesium sulfate, the solvent was removed and the residue was purifiedby silica gel chromatography (developing solvent: hexane/ethylacetate=3/1). An aldehyde compound was obtained. (Yield: 4.2 g (65%))

Step III

The aldehyde compound (3.92 g, 14.1 mmol) was dissolved with methanol(20 mL). Into this, potassium carbonate (400 mg) and water (1 mL) wereadded at room temperature and the solution was stirred overnight. On thenext day, the solution was poured into brine water and extracted byether. The ether layer was dried over anhydrous magnesium sulfate. Afterremoving the magnesium sulfate, the solvent was removed and the residuewas purified by silica gel chromatography (developing solvent:hexane/acetone=1/1). An aldehyde alcohol compound was obtained. (Yield:3.2 g (96%))

Step IV

The aldehyde alcohol (5.8 g, 24.7 mmol) was dissolved with anhydrous THF(60 mL). Into this, triethylamine (3.8 mL, 27.1 mmol) was added and thesolution was cooled by ice-bath. Acrolyl chloride (2.1 mL, 26.5 mmol)was added and the solution was maintained at 0° C. for 20 minutes.Thereafter, the solution was allowed to warm up to room temperature andstirred at room temperature for 1 hour, at which point TLC indicatedthat all of the alcohol compound had disappeared. The solution waspoured into brine water and extracted by ether. The ether layer wasdried over anhydrous magnesium sulfate. After removing the magnesiumsulfate, the solvent was removed and the residue acrylate compound waspurified by silica gel chromatography (developing solvent:hexane/acetone=1/1). The compound yield was 5.38 g (76%), and thecompound purity was 99% (by GC).

(d) Synthesis of Non-Linear-Optical Chromophore 7-DCST

The non-linear-optical precursor 7-DCST (7 member ring dicyanostyrene,4-homopiperidinobenzylidene malononitrile) was synthesized according tothe following two-step synthesis scheme:

A mixture of 4-fluorobenzaldehyde (17.8 g, 143 mmol), homopiperidine(15.0 g, 151 mmol), lithium carbonate (55 g, 744 mmol), and DMF (100 mL)were stirred at 50° C. for 16 hr. Water (500 mL) was added to thereaction mixture. The products were extracted with ether (1 L). Afterremoval of ether, the crude products were purified by silica gel columnchromatography using hexanes-ethyl acetate (9:1) as eluent.4-(Dimethylamino)pyridine (100 mg, 0.82 mmol) was added to a solution ofthe 4-homopiperidinobenzaldehyde (18.2 g, 89.5 mmol) and malononitrile(9.1 g, 137.8 mmol) in methanol (60 mL). The reaction mixture was keptat room temperature and the product was collected by filtration andpurified by recrystallization from dichloromethane. Yield (17.1 g, 48%)

(e) C₆₀ Fullerene

C₆₀ fullerene was purchased from MER, Tucson, Ariz. The purity of C₆₀was 98% and up.

(f) Other Materials

Beside the above monomers and initiator, other chemicals, such as copperbromide and bipyridine were purchased from Aldrich Chemicals, Milwaukee,Wis.

Production Example 2

Preparation of C₆₀ Containing Charge Transport Homopolymer (TPD AcrylateType)

(a) Preparation of TPD Homo-Polyacrylate Precursor Intermediate

N-[(meth)acroyloxypropylphenyl]-N,N′,N′-triphenyl-(1,1′-biphenyl)-4,4′-diamine(TPD acrylate) (1.6 g, 2.6 mmol), bipyridine (82 mg, 0.525 mmol; as aligand), ethylene bis(2-bromo (chloro)-2-methylpropionate) (Br-BMP) (36mg, 0.105 mmol; as a polymerization initiator), and toluene (2.1 g) wereput into a three-necked flask. After purging by argon gas for 1 hour,CuBr (30 mg, 0.209 mmol; as transition metal catalyst) were added intothis solution. Then, the solution was heated to 90° C., while continuingto purge with argon gas.

After 18 hrs polymerization, reaction mixture was checked by H-NMR todetermine the conversion ratio and it was found out to be 71% based onintegration ratio of polymer and monomer related methylene (—COOCH₂—CH₂—CH ₂—) signals. The polymer solution was diluted with toluene, andthen filtered to remove non-dissolved impurities. The polymer wasprecipitated from the solution by adding methanol, the resulting polymerprecipitate was collected and washed in diethyl ether and methanol toremove unreacted acrylate monomer and other impurities. The whitepolymer powder was collected and dried.

The weight average and number average molecular weights were measured bygel permeation chromatography, using a polystyrene standard. The resultswere Mp (peak top of molecular weight distribution)=8,317.

(b) Preparation of C₆₀-Containing TPD Homo-Polyacrylate Polymer

The obtained precursor polymer (680 mg), bipyridine (40 mg, 0.256 mmol;as a ligand), and chlorobenzene (4 mL) were put into a three-neckedflask. After purging by argon gas for 1 hour, CuBr (14 mg, 0.100 mmol;as transition metal catalyst) and C₆₀ (80 mg, 0.111 mmol) were addedinto this solution. Then, the solution was heated to 90° C., whilecontinuing to purge with argon gas.

After 18 hrs polymerization, chlorobenzene was evaporated by rotaryevaporator and the residue mixture was dissolved with THF. Then thepolymer solution was filtered to remove non-dissolved impurities by 0.2μm pore size PTFE filter, because unreacted C₆₀ can not be soluble withTHF. The polymer was precipitated from the solution by adding methanol,the resulting polymer precipitate was collected and washed in methanolto remove impurities. The black polymer powder was collected and dried.

The molecular weights were measured by gel permeation chromatography,using a polystyrene standard. The results were Mp (peak top of molecularweight distribution)=10,413. The molecular weight difference for Mpbetween precursor and C₆₀-containing polymers is 2,096, which is almostequivalent to two C₆₀ molecule molecular weight.

Production Example 3

Preparation of C₆₀-Containing Copolymer (Tetra-Functional Type)

(a) Preparation of Co-Polyacrylate Precursor Intermediate

N-[(meth)acroyloxypropylphenyl]-N,N′,N′-triphenyl-(1,1′-biphenyl)-4,4′-diamine(TPD acrylate) (2.0 g, 3.24 mmol), the non-linear-optical precursormonomer 5-[N-ethyl-N-4-formylphenyl]amino-pentyl acrylate (0.60 g, 2.07mmol), the plasticzer monomer 2-ethylhexyl acrylate (0.14 g, 0.76 mmol),bipyridine (220 mg, 1.40 mmol; as a ligand), ethylene bis(2-bromo(chloro)-2-methylpropionate) (Br-BMP) (100 mg, 0.28 mmol; as apolymerization initiator), and toluene (4.2 g) were put into athree-necked flask. After purging by argon gas for 1 hour, CuBr (80 mg,0.56 mmol; as transition metal catalyst) were added into this solution.Then, the solution was heated to 80° C., while continuing to purge withargon gas.

After 18 hrs polymerization, reaction mixture was checked by H-NMR todetermine the conversion ratio and it was found out to be almost 100%based on integration ratio of polymer and monomer related methylene(—COOCH ₂—CH₂—CH ₂—) signals. The polymer solution was diluted withtoluene, and then filtered to remove non-dissolved impurities. Thepolymer was precipitated from the solution by adding methanol, theresulting polymer precipitate was collected and washed in diethyl etherand methanol to remove unreacted acrylate monomers and other impurities.The white polymer powder was collected and dried. The weight average andnumber average molecular weights were measured by gel permeationchromatography, using a polystyrene standard. The results were Mw(weight average molecular weight)=7,825.

(b) Preparation of C₆₀-Containing TPD Co-Polyacrylate Polymer

The obtained precursor polymer (1.6 g), bipyridine (120 mg, 0.800 mmol;as a ligand), and chlorobenzene (10 mL) were put into a three-neckedflask. After purging by argon gas for 1 hour, CuBr (46 mg, 0.32 mmol; astransition metal catalyst) and C₆₀ (216 mg, 0.30 mmol) were added intothis solution. Then, the solution was heated to 90° C., while continuingto purge with argon gas.

After 18 hrs polymerization, chlorobenzene was evaporated by rotaryevaporator and the residue mixture was dissolved with THF. Then thepolymer solution was filtered to remove non-dissolved impurities by 0.2μm pore size PTFE filter, because unreacted C₆₀ can not be soluble withTHF. The polymer was precipitated from the solution by adding methanol,the resulting polymer precipitate was collected and washed in methanolto remove impurities. The black polymer powder was collected and dried.

The weight average and number average molecular weights were measured bygel permeation chromatography, using a polystyrene standard. The resultswere Mw (weight average molecular weight distribution)=12,857. There isthe molecular weight difference between precursor and C₆₀-containingpolymers, which means C₆₀ molecule incorporation.

(c) Conversion of CHO Form into Dicyano Form

To convert the precursor CHO group in the polymer chain into group withdicyano functional group, the precipitate (1.68 g) was dissolved withCDCl₃ (8 mL). Into this solution, dicyanomalonate (340 mg, 5.15 mmol)and dimethylaminopyridine (60 mg) were added, and the resulting solutionwas stirred overnight at 40° C. The polymerization reaction was allowedto proceed, and the resulting polymer solution was diluted with toluene,followed by filtration to remove impurities and polymer precipitationinto methanol. The precipitated polymer was collected and washed inmethanol. The polymer yield was essentially 100%.

Production Reference 1

Non-C₆₀-Containing Charge Transport Homopolymer (TPD Acrylate Type)

The obtained TPD homo-polyacrylate precursor intermediate in ProductionExample 2 is used for the non-C₆₀-containing Charge TransportHomopolymer (TPD acrylate type). Obviously, the weight average andnumber average molecular weights were measured by gel permeationchromatography, using a polystyrene standard. The results were Mp (peaktop of molecular weight distribution)=8,317.

Production Reference 2

Non-C₆ Containing Copolymer (Tetra-Functional Type)

The obtained co-polyacrylate precursor intermediate in ProductionExample 3 (0.85 g) was dissolved with CDCl₃ (5 mL). Into this solution,dicyanomalonate (170 mg, 2.58 mmol) and dimethylaminopyridine (20 mg)were added, and the resulting solution was stirred overnight at 40° C.The polymerization reaction was allowed to proceed, and the resultingpolymer solution was diluted with toluene, followed by filtration toremove impurities and polymer precipitation into methanol. Theprecipitated polymer was collected and washed in methanol. The polymeryield was essentially 100%.

Example 1

Preparation of Photorefractive Composition

A photorefractive composition testing sample was prepared. Thecomponents of the composition were as follows:

(i) C₆₀-containing Charge Transport Homopolymer 30 wt % (TPD acrylatetype) prepared in Production Example 2 (ii) Charge Transport Homopolymer(TPD acrylate type, 30 wt % non-C₆₀-containing type) prepared inProduction Reference 1 (iii) Synthesized chromophore of 7-DCST 25 wt %(iv) Synthesized plasticizer of TPD-aceate 15 wt %

To prepare the composition, the components listed above were dissolvedwith toluene and stirred at room temperature. After removing the solventby rotary evaporator and vacuum pump, the residue was scratched andgathered.

To make testing samples, this powdery residue mixture was put on a slideglass and melted at 150° C. to make a 200-300 μm thickness film, orpre-cake. Small portions of this pre-cake were taken off and sandwichedbetween indium tin oxide (ITO) coated glass plates separated by a 105 μmspacer to form the individual samples.

Measurement 1

Diffraction Efficiency

The diffraction efficiency was measured at 633 nm by four-wave mixingexperiments. Steady-state and transient four-wave mixing experimentswere done using two writing beams making an angle of 20.5 degree in air;with the bisector of the writing beams making an angle of 60 degreerelative to the sample normal.

For the four-wave mixing experiments, two s-polarized writing beams withequal intensity of 0.2 W/cm² in the sample were used; the spot diameterwas 600 μm. A p-polarized beam of 1.7 mW/cm² counter propagating withrespect to the writing beam nearest to the surface normal was used toprobe the diffraction gratings; the spot diameter of the probe beam inthe sample was 500 μm. The diffracted and the transmitted probe beamintensities were monitored to determine the diffraction efficiency. Thediffraction efficiency of example 1 is 8% with biased voltage 6 kV/em.

Measurement 2

Response Time

The diffraction efficiency were measured as a function of the appliedfield, using a procedure similar to that described in Measurement 1, byfour-wave mixing experiments at 633 nm with s-polarized writing beamsand a p-polarized probe beam. The angle between the bisector of the twowriting beams and the sample normal was 60 degree. The writing beams hadequal optical powers of 0.45 mW/cm², leading to a total optical power of0.5 mW on the polymer, after correction for reflection losses. The beamswere collimated to a spot size of approximately 500 μm. The opticalpower of the probe was 4 mW. The measurement of the grating buildup timewere done as follows: an electric field of 40 V/μm was applied to thesample, and the sample was illuminated with one of the two writing beamsand the probe beam for 100 ms. Then, the evolution of the diffractedbeam was recorded. The response time was estimated as the time based onthe equation in below, in which the smaller number is defined as theresponse time between J₁ and J₂.

η(t)=A sin² [B(1−a ₁ e ^(−t/J1) −a ₂ e ^(−t/J2))]with

a ₁ +a ₂=1

where η(t) is the diffraction efficiency at time t, and A, B, a₁, and a₂are fitting parameters, J₁ and J₂ are the grating build-up times.Between J₁ and J₂, the smaller number is defined as the response time.The response time of example 1 is 18 msec with biased voltage 6 kV/μm.

Measurement 3

Testing Sample Stability

The stability of a testing sample was determined after certain period(days) storage in room temperature or 60° C. The testing samples wereobserved either in bare eye or by microscope whether crystallizationoccurred or not in samples. Even if tiny crystallization occurred, thesample was categorized as “phase separated.” Otherwise, the sample wascategorized as “No phase separated.”

Example 2

A photorefractive composition was obtained in the same manner as in theExample 1 except that composition ratio was changed to the ratio asdescribed in below.

The components of the composition were as follows:

(i) C₆₀-containing Charge Transport Homopolymer 15 wt % (TPD acrylatetype) prepared in Production Example 2 (ii) Charge Transport Homopolymer(TPD acrylate type, 45 wt % non-C₆₀-containing type) prepared inProduction Reference 1 (iii) Synthesized chromophore of 7-DCST 25 wt %(iv) Synthesized plasticizer of TPD-aceate 15 wt %

The diffraction efficiency and the response time of example 2 are 8% and13 msec with biased voltage 6 kV/μm, respectively.

Example 3

A photorefractive composition was obtained in the same manner as in theExample 1 except that C₆₀-containing Copolymer prepared in ProductionExample 3 was used and composition ratio was changed to the ratio asdescribed in below.

The components of the composition were as follows:

(i) C₆₀-containing Copolymer (TPD/DCST/2-EHA poly 15 wt % acrylatecopolymer type) prepared in Production Example 3 (ii) Copolymer(TPD/DCST/2-EHA poly acrylate copolymer 45 wt % type, non-C₆₀-containingtype) prepared in Production Reference 2 (iii) Synthesized chromophoreof 7-DCST 25 wt % (iv) Synthesized plasticizer of TPD-aceate 15 wt %

The diffraction efficiency and the response time of example 3 are 9% and12 msec with biased voltage 6 kV/μm, respectively.

Comparative Example 1

A photorefractive composition testing sample was prepared. Thecomponents of the composition were as follows:

(i) Charge Transport Homopolymer (TPD acrylate type,   60 wt %non-C₆₀-containing type) prepared in Production Reference 1 (ii)Synthesized chromophore of 7-DCST 28.6 wt % (iii) Synthesizedplasticizer of TPD-aceate 10.9 wt %

The diffraction efficiency and the response time of comparative example1 are 23% and 208 msec with biased voltage 6 kV/μm, respectively. Noaddition of C₆₀, which means this composition gave very slow responsetime due to the absence of C₆₀.

Comparative Example 2

A photorefractive composition testing sample was prepared. Thecomponents of the composition were as follows:

(i) Copolymer (TPD/DCST/2-EHA poly acrylate copolymer 60 wt % type,non-C₆₀-containing type) prepared in Production Reference 2 (ii)Synthesized chromophore of 7-DCST 25 wt % (iii) Synthesized plasticizerof TPD-aceate 15 wt %

The diffraction efficiency of comparative example 2 is 1.5% with biasedvoltage 6 kV/μm. The diffraction signal was too weak to evaluate theresponse time. No addition of C₆₀ nor C₆₀ containing copolymer, whichmeans this composition gave small diffraction efficiency due to theabsence of C₆₀ in this case.

What is claimed is:
 1. A polymer represented by a formula selected fromthe group consisting of formulae (I), (II), (III) and (IV):

wherein R₀ represents a hydrogen atom or alkyl group with up to 10carbons; R is selected from the group consisting of a hydrogen atom, alinear alkyl group with up to 10 carbons, a branched alkyl group with upto 10 carbons, and an aromatic group with up to 10 carbons; C ball is afullerene; A represents a repeating structure comprising at least one ofthe below repeating unit 1 and repeating unit 2;

wherein p is an integer of 2 to 6; A′ represents a repeating structurecomprising at least one of the below repeating unit 1 and repeating unit2;

wherein Z is represented by a structure selected from the groupconsisting of structures (i), (ii) and (iii); and Z′ is represented byformula (0);

wherein Q represents an alkylene group, with or without a hetero atom;R₁ is selected from the group consisting of a hydrogen atom, a linearalkyl group with up to 10 carbons, a branched alkyl group with up to 10carbons, and an aromatic group with up to 10 carbons; G is a grouphaving a bridge of π-conjugated bond; and Eacpt is an electron acceptorgroup; wherein the structures (i), (ii) and (iii) are:

wherein Q represents an alkylene group, with or without a hetero atom;Ra₁, Ra₂, Ra₃, Ra₄, Ra₅, Ra₆, Ra₇, and Ra₈ are independently selectedfrom the group consisting of a hydrogen atom, a linear alkyl group withup to 10 carbons, a branched alkyl group with up to 10 carbons, and anaromatic group with up to 10 carbons;

wherein Rb₁-Rb₂₇ are each independently selected from the groupconsisting of a hydrogen atom, a linear alkyl group with up to 10carbons, a branched alkyl group with up to 10 carbons, and an aromaticgroup with up to 10 carbons;

wherein Rc₁-Rc₁₄ are each independently selected from the groupconsisting of a hydrogen atom, a linear alkyl group with up to 10carbons, a branched alkyl group with up to 10 carbons, and an aromaticgroup with up to 10 carbons.
 2. The polymer of claim 1, wherein G informula (0) is represented by a structure selected from the groupconsisting of the structures (iv), (v) and (vi); wherein structures(iv), (v) and (vi) are:

wherein, in both structures (iv) and (v), Rd₁-Rd₄ are each independentlyselected from the group consisting of a hydrogen atom, a linear alkylgroup with up to 10 atoms, a branched alkyl group with up to 10 atoms,and an aromatic group with up to 10 carbons; R₂ is selected from thegroup consisting of a hydrogen atom, a linear alkyl group with up to 10atoms, a branched alkyl group with up to 10 atoms, and an aromatic groupwith up to 10 carbons;

wherein R₇, R₇′, R₇″, and R₇′″ each independently represent hydrogen ora linear or branched alkyl group with up to 10 carbons; and whereinEacpt in formula (0) is an electron acceptor group and represented by astructure selected from the group consisting of the structures;

wherein R₉, R₁₀, R₁₁, and R₁₂ are each independently selected from thegroup consisting of a hydrogen atom, a linear alkyl group with up to 10atoms, a branched alkyl group with up to 10 atoms, and an aromatic groupwith up to 10 carbons.
 3. The polymer of claim 1, wherein the formulae(I), (II), (III) and (IV) are represented by the following formulae(Ia), (IIa), (IIIa) and (IVa), respectively:

wherein R₀, R, Z, and Cball each have the same meaning as in formula(I); and k is an integer of 10 to 10,000;

wherein R₀, R, Z, and Cball each have the same meaning as in formula(I); and m and n are an integer of 5 to 10,000, respectively;

wherein R₀, Z, and Cball each have the same meaning as in formula (I);and k is an integer of 10 to 10,000;

wherein Z and Cball each have the same meaning as in formula (I); and kis an integer of 10 to 10,000.
 4. The polymer of claim 1, wherein theformulae (I), (II), (III) and (IV) are represented by the followingformulae (Ib), (IIb), (IIIb) and (IVb), respectively:

wherein R₀, R, Z′, and Cball each have the same meaning as in formula(I); and k is an integer of 10 to 10,000;

wherein R₀, R, Z′, and Cball each have the same meaning as in formula(I); and m and n are an integer of 5 to 10,000, respectively;

wherein R₀, Z′, and Cball each have the same meaning as in formula (I);and k is an integer of 10 to 10,000;

wherein Z′ and Cball each have the same meaning as in formula (I); and kis an integer of 10 to 10,000.
 5. The polymer of claim 1, wherein theformulae (I), (II), (III) and (IV) are represented by the followingformulae (Ic), (IIc), (IIIc) and (IVc), respectively:

wherein R₀, R, Z, Z′, and Cball each have the same meaning as in formula(I); x is an integer of 5 to 10,000; and y is an integer of 5 to 10,000;

wherein R₀, R, Z, Z′, and Cball each have the same meaning as in formula(I); x is an integer of 5 to 10,000; y is an integer of 5 to 10,000; ris an integer of 5 to 10,000; and s is an integer of 5 to 10,000;

wherein R₀, Z, Z′, and Cball each have the same meaning as in formula(I); and x is an integer of 5 to 10,000; and y is an integer of 5 to10,000;

wherein Z, Z′, and Cball each have the same meaning as in formula (I);and x is an integer of 5 to 10,000; and y is an integer of 5 to 10,000.6. The polymer of claim 1, wherein the polymer has a glass transitiontemperature of about 125° C. or less.
 7. A method for producing afullerene-containing polymer comprising: polymerizing a monomer by aliving radical polymerization technique to form a polymer, wherein themonomer comprises a structure selected from the group consisting ofstructures (i), (ii) and (iii); and reacting the polymer with afullerene to produce a fullerene-containing polymer, wherein thefullerene-containing polymer is represented by a formula selected fromthe group consisting of the formulae (Ia), (IIa), (IIIa) and (IVa) setforth in claim 3:

wherein Q represents an alkylene group, with or without a hetero atom;Ra₁, Ra₂, Ra₃, Ra₄, Ra₅, Ra₆, Ra₇, and Ra₈ are independently selectedfrom the group consisting of a hydrogen atom, a linear alkyl group withup to 10 carbons, a branched alkyl group with up to 10 carbons, and anaromatic group with up to 10 carbons;

wherein Rb₁-Rb₂₇ are each independently selected from the groupconsisting of a hydrogen atom, a linear alkyl group with up to 10carbons, a branched alkyl group with up to 10 carbons, and an aromaticgroup with up to 10 carbons;

wherein Rc₁-Rc₁₄ are each independently selected from the groupconsisting of a hydrogen atom, a linear alkyl group with up to 10carbons, a branched alkyl group with up to 10 carbons, and an aromaticgroup with up to 10 carbons.
 8. The method of claim 7, wherein theliving radical polymerization technique comprises contacting the monomerwith a transition metal catalyst selected from the group consisting ofcopper bromide and copper chloride.
 9. The method of claim 7, whereinthe living radical polymerization technique comprises contacting themonomer with a polymerization initiator selected from the groupconsisting of α-halogenated ester and α-halogenated styrene.
 10. Themethod of claim 8, wherein the living radical polymerization techniquecomprises contacting the transition metal with a ligand selected fromthe group consisting of bipyridines, mercaptans, and trifluorates.
 11. Amethod for producing a fullerene-containing polymer comprising:polymerizing a monomer by a living radical polymerization technique toform a polymer, wherein the monomer comprises a structure represented bythe formula (0); and reacting the polymer with a fullerene to produce afullerene-containing polymer, wherein the fullerene-containing polymeris represented by a formula selected from the group consisting of theformulae (Ib), (IIb), (IIIb) and (IVb) set forth in claim 4:

wherein Q represents an alkylene group, with or without a hetero atom;R₁ is selected from the group consisting of a hydrogen atom, a linearalkyl group with up to 10 carbons, a branched alkyl group with up to 10carbons, and an aromatic group with up to 10 carbons; G is a grouphaving a bridge of π-conjugated bond; and Eacpt is an electron acceptorgroup.
 12. The method of claim 11, wherein G in formula (0) isrepresented by a structure selected from the group consisting of thestructures (iv), (v) and (vi); wherein structures (iv), (v) and (vi)are:

wherein, in both structures (iv) and (v), Rd₁-Rd₄ are each independentlyselected from the group consisting of a hydrogen atom, a linear alkylgroup with up to 10 atoms, a branched alkyl group with up to 10 atoms,and an aromatic group with up to 10 carbons; R₂ is selected from thegroup consisting of a hydrogen atom, a linear alkyl group with up to 10atoms, a branched alkyl group with up to 10 atoms, and an aromatic groupwith up to 10 carbons;

wherein R₇, R₇′, R₇″, and R₇′″ each independently represent hydrogen ora linear or branched alkyl group with up to 10 carbons; and whereinEacpt in formula (0) is an electron acceptor group and represented by astructure selected from the group consisting of the structures;

wherein R₉, R₁₀, R₁₁ and R₁₂ are each independently selected from thegroup consisting of a hydrogen atom, a linear alkyl group with up to 10atoms, a branched alkyl group with up to 10 atoms, and an aromatic groupwith up to 10 carbons.
 13. The method of claim 11, wherein the livingradical polymerization technique comprises contacting the monomer with atransition metal catalyst selected from the group consisting of copperbromide and copper chloride.
 14. The method of claim 11, wherein theliving radical polymerization technique comprises contacting the monomerwith a polymerization initiator selected from the group consisting ofα-halogenated ester and α-halogenated styrene.
 15. The method of claim13, wherein the living radical polymerization technique comprisescontacting the transition metal with a ligand selected from the groupconsisting of bipyridines, mercaptans, and trifluorates.
 16. A methodfor producing a fullerene-containing polymer comprising: copolymerizingat least a first monomer and a second monomer by a living radicalpolymerization technique to form a polymer, wherein the first monomercomprises a structure selected from the group consisting of structures(i), (ii) and (iii); and reacting the polymer with a fullerene toproduce a fullerene-containing polymer, wherein the fullerene-containingpolymer is represented by a formula selected from the group consistingof the formulae (Ic), (IIc), (IIIc) and (IVc) set forth in claim 5:

wherein Q represents an alkylene group, with or without a hetero atom;Ra₁, Ra₂, Ra₃, Ra₄, Ra₅, Ra₆, Ra₇, and Ra₈ are independently selectedfrom the group consisting of a hydrogen atom, a linear alkyl group withup to 10 carbons, a branched alkyl group with up to 10 carbons, and anaromatic group with up to 10 carbons;

wherein Rb₁-Rb₂₇ are each independently selected from the groupconsisting of a hydrogen atom, a linear alkyl group with up to 10carbons, a branched alkyl group with up to 10 carbons, and an aromaticgroup with up to 10 carbons;

wherein Rc₁-Rc₁₄ are each independently selected from the groupconsisting of a hydrogen atom, a linear alkyl group with up to 10carbons, a branched alkyl group with up to 10 carbons, and an aromaticgroup with up to 10 carbons; and wherein the second monomer comprises astructure represented by the formula (0):

wherein R₁ is selected from the group consisting of a hydrogen atom, alinear alkyl group with up to 10 carbons, a branched alkyl group with upto 10 carbons, and an aromatic group with up to 10 carbons; G is a grouphaving a bridge of π-conjugated bond; and Eacpt is an electron acceptorgroup.
 17. The method of claim 16, wherein G in formula (0) isrepresented by a structure selected from the group consisting of thestructures (iv), (v) and (vi); wherein structures (iv), (v) and (vi)are:

wherein, in both structures (iv) and (v), Rd₁-Rd₄ are each independentlyselected from the group consisting of a hydrogen atom, a linear alkylgroup with up to 10 atoms, a branched alkyl group with up to 10 atoms,and an aromatic group with up to 10 carbons; R₂ is selected from thegroup consisting of a hydrogen atom, a linear alkyl group with up to 10atoms, a branched alkyl group with up to 10 atoms, and an aromatic groupwith up to 10 carbons;

wherein R₇, R₇′, R₇″, and R₇′″ each independently represent hydrogen ora linear or branched alkyl group with up to 10 carbons; and whereinEacpt in formula (0) is an electron acceptor group and represented by astructure selected from the group consisting of the structures;

wherein R₉, R₁₀, R₁₁, and R₁₂ are each independently selected from thegroup consisting of a hydrogen atom, a linear alkyl group with up to 10atoms, a branched alkyl group with up to 10 atoms, and an aromatic groupwith up to 10 carbons.
 18. The method of claim 16, wherein the livingradical polymerization technique comprises contacting the monomer with atransition metal catalyst selected from the group consisting of copperbromide and copper chloride.
 19. The method of claim 16, wherein theliving radical polymerization technique comprises contacting the monomerwith a polymerization initiator selected from the group consisting ofα-halogenated ester and α-halogenated styrene.
 20. The method of claim18, wherein the living radical polymerization technique comprisescontacting the transition metal with a ligand selected from the groupconsisting of bipyridines, mercaptans, and trifluorates.
 21. Acomposition comprising a sensitizer and a polymer according to claim 1,wherein the composition exhibits photorefractive ability.
 22. Thecomposition of claim 21, wherein the polymer has a glass transitiontemperature about 125° C. or less.
 23. The composition of claim 21,wherein the composition has a response time of no longer than about 50miliseconds as measured under an electric field of no greater than about60 V/μm.
 24. The composition of claim 21, further comprising aplasticizer.